Exposure to acute single-incident trauma is unfortunately common for children. Injury (unintentional and violence-related), disasters and terrorism, and other potentially traumatic events affect millions of children each year. Trauma-exposed children exhibit a wide variation in psychological and functional adaptation and outcomes, with a significant proportion developing traumatic stress or other psychological sequelae which can impact child health and functioning. Although the vast majority of studies examining these sequelae have been cross-sectional, a growing body of prospective studies have assessed children's adaptation over time following acute trauma exposure. Due to resource limitations, many prospective studies involve small samples, and variation in measures and assessment timing make cross-study comparisons challenging. Integrative cross- study analyses using individual patient data are possible, but require substantial attention to dataset integration and data harmonization that is generally beyond the reach of individual investigators. Our overarching objective is to create a research resource for the child trauma field that will enhance the utility and value of child trauma studies by allowing integrative cross-study analyses and promoting the use of common data elements across future studies. In the proposed R03-funded project, we will leverage the solid framework of an existing set of 20 datasets and related expertise in data harmonization, to create the Prospective studies of Acute Child Trauma and Recovery (PACT/R) data archive. The PACT/R archive will include US and international prospective studies with data from at least 31 studies representing more than 7000 children from 6 countries exposed to a wide range of potentially traumatic events including injury, violence, and natural disaster. Project aims include (Aim 1) Adding at least 11 new datasets (data from >4000 children) and establishing reproducible templates for data intake and cleaning, as well as application of meta- data and creating a searchable database of studies, variables, and measures. (Aim 2) Guided by an expert advisory panel, we will create, apply, and share algorithms for data harmonization of key variables and constructs to enable integrative cross-study data analyses. (Aim 3) We will promote awareness of the PACT/R archive as a resource for data sharing and secondary data analysis via a PACT/R webpage, and (Aim 4) convene an expert advisory panel to identify challenges to data harmonization as well as gaps in available data from acute child trauma studies, and recommend common data elements for future prospective studies in this area of research. Project results will advance data sharing, enable secondary analysis of prospective data on child trauma and recovery by the scientific community that would not otherwise be possible, and enhance the value of future research in this crucial area of study by recommending core data elements.